<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <style>
        article{
            width: 1200px;
            border: solid 2px #ddd;
            height: 600px;
            margin:0 auto;
            box-sizing: border-box;
            padding-top:200px ;
        }

        article>div{
            background-color: blueviolet;
            box-sizing: border-box;
            height:200px;
            border:solid 1px #ddd;
            background-clip: content-box;
            padding: 10px;
            float:left;
        }
        article>div:nth-child(1){
            width: 300px;
            float:left;
        }
        article>div:nth-child(2){
            width: 600px;
            margin-left: 10px;
        }
        article>div:nth-child(3){
            width:280px;
            float: right;
        }
    </style>
   <article>
       <div>

       </div>
       <div>

       </div>
       <div>

    </div>
   </article> 
</body>
</html>